Driftmeter simulator



2 Sheets-Sheet 1 Filed March 18, 1954 .FIG," 2

INVENTORS RICHARD D. MAY NILS B. MICKELSON Em; fi f AGENT.

United States Patent SIMULATOR Richardi D;'Mayiwestport,ahdfNils B; Mickelsou, Stamford, Connr; assignors' to The Reflectone Corporation, Stamford,'" Conn., a"corporation nf Connecticut ApplicationMarchlti,1954,.Serial No. 417,089 "6 Claims.-" -(Cl$- 35-5102) This.invention relates 1 to a' training. device for. aircraft navigators-and has; specific :reference toan .instrument for a teaching .the reading of drift-angle andof groundspeed as encountered in aircraft navigation.. if he: device described hereinafter is-qused primarily for ,synthetic training, i.- e. (for classroomeinstructiona;on ground. whereby the operaation-ofponventional. airborne driftmeters is simulated in a realistic gand gaceuratemanner.

One of the objects of this inventionisuto provide a synthetic training device which simulates .the presentation and goperation rofipperational. :dri ftmeters.

::Ariothenobject;ofrthiseinventionisto provide a drift- (meter simulator which-may-bcused. forinstructional purposes; particularlyfonreading.of drift angle and of ground speed. finAnOthQt-EQbjfiCl ofit-his invention is to provide a drifttmetersimulator which simulates in .arealistic manner the If appearancelof thezground when takingdriftmeter readings -,rat;convent-ional flyingaltitudes.

Still-.anothen.objecttof.thisiinvention is a provision of illuminating 1 :means .rforwsimulating :the appearance of a. ground :aswiewed from:an aircraft .during day light and during inight.

-In;;general-, :the inventionicomprises a cradle mounted forpivotal:motionzandsupporting a movable belta Means areprovided. to;idrive:.said :belt at a: speed proportional to ground speed, oil the .aircraft .simulated. A pi otally :;mounted 1light:,.defiecting; means ispositioned for com- -:munication-with; a .portions'ofithe .belt and receives an :image therefrom. .Anoptical system is provided which presents thetimage received by theirnage deflecting means .at a .stationarytpoint. Further means are provided to pivot thecradle'aboutan.anglezcorresponding to the drift off the, aircraft simulated.

For. a lbetter understanding of: the present invention together with other. and further objects thereof reference is made to:.the following description .taken in connection withaccompanyingdrawings in which;

Figure 1. is an; elevationview of :the in. section;

,Figure 2 is a fragmentary view incorporating a modificaltion ofztheconstruction shown in Figure 1;

Figure 3is aaview of a. portion of the device, shown in --'shiftedposition;

Figure 4 is a schematic vievvnofthe reticle used in the '1 device;

Figure 5 is auschematic view of an alternate optical Larrangement.

- Referring to Figure 1,numeral 10, identifies a station- :ary frame whichsupportsnearly all parts of the driftmeter. A= top plate 11 serves to exclude ambient light from reaching the inside of; the'frame. A synchro 12 and a servomotor 13 which form partof a conventional servo mechanism a are coupled together by coupling 14. The stators of the synchro 12 and motor 13 are retained in an annular sleeve 15 which is rotatable-with respect to stationary frame by-"virtue of ball bearings 16 and 17. Sleeve driftmeter partly gears 23 and 24; shaft 25,

andspur gear 26, its rotation to annular spur gearr27 which is attached. to the periphery "-of sleeve 15. The rotation of sleeve and of the stators of the electro-m'echanical.components 'oftheservo systern isindicatedtondial128. operatingin combination with .pointer 29. attached totsha'ft 22.

The rotoreofsynchroi12'is equipped with a shaft 30 which is rigidly connected=to aecradle 31. Cradle 31 thereforepivotspin response to rotation produced by shaft 15 30. The lweight of t cradle .31: is relieved by means of a ballibearing 32 supportedtinrframe 10.

The cradle31supp0rts apair-of spaced rollers 33Land 34 respectively. .lStepped-1roller- 34is "driven via intermediate roller136;by aavariable: speed drivemeans 35,

. preferably avariable speed electric motor having a roller mounted ;on. itsioutput sliaft. A flexible belt 37is supporteda about theserollersand is driven in response to .motion impartedzvtoifthe roller 34 by variable'speed 1:.meansz35. 0.The:belt37=is equippedflWith discernible mark- :.ings,:.or:in :the preferredembo'diment, an aerialphotograph is mounted upontheouter surface of a rubber belt.

-Belt z37 traverses a, substanti'ally straight path 38' which and frictionallyengaging roller '49 .is disposedzintermediate rollersl33 and 34. It will be ap- ..parentxthatsthe frollers may beficrow ned in order that the belt remainicentered.

. .A light: reflecting mirror 40 is support'edonabracket 41 .whichaisnnounted =f0r pivotal motion with shaft 42 held in standoff bracket 43. The mirror is mounted in such a mannerthat it will reflect an-imagefrom apart'of the substantially straight; portion 38 of mirror is pivoted about the 1 axis or the belt 37.- As the shaft'42, it scans the #:substantially straightportion 38.

Movement of=mirror 40is etfected by knob 44*fastened to shaft45, through bevel-gear 46, a matching bevel. gear (notshown); -shaft=' 47,"=rbller 48 fastened to shaft 47 attached to shaft 42. A detent mechanism 50, the purpose of which will be explainedlater; is provided in order to obtain predetermined calibrated rotation of knob'44'relative to stationary'frame a through a suitable lens The image reflected bymirror 40 is transmitted to a pair of stationary mirrors 51 and 52, reflected from there 53 contained in lens barrel 54, to form an image in the plane of -reticle55. The image. is seen by a studentap'plying his eye at point 57 and looking through eyepiece56at the reticle 55.

The'constructionof the reticle 55 is schematically shown in Figure 4 whereinthereticle is equipped. with hair lines 63 in the longitudinal directionand with lines 64 in the transverse direction. purposes.

The operation of this device may be visualized as f0llows: By way of the servo mechanism anv instructor applies a signal to the synchro 12. causing shaft 30 and cradle 31 to assume an angular position which is pro- These hair linesserve for indexing portional to the drift angle bfthe aircraftsimulated. The

synchro stator" and" sleeve 15 are of motor 35, the terspeed corresponding to the areas is 3 64. If the student fixes his sight on a selected image, this image will move along a straight line (for instance dotted line 65) as the belt traverses the substantially flat portion 38. Seeing that this object fails to move parallel to the longitudinal index lines 63, it will become apparent that a drift exists. In order to determine the drift angle, the student will turn knob 18 which causes sleeve 15 to rotate thereby moving synchro 12 relative to frame until the selected terrain markings move parallel to the longitudinal indexing lines 63 as shown by dotted line 66. When this occurs the amount of drift introduced by the instructor and corrected by the student will be apparent by virtue of the combination of dial 28 and indicator 29. In this condition the cradle 31 has been returned to its vertical position;

In order to determine the ground speed of the simulated aircraft, the student selects a certain marking on the belt and maintains an image of this marking stationary with respect to transverse indexing lines 64. This is accomplished by turning knob 44 in such a way that pivotally mounted mirror 40 follows the selected marking as this marking traverses the substantially straight portion of the belt. Since knob 44 is equipped with a detent mechanism 50, the time necessary to turn this knob from one detent to the next detent will be a measure of the speed with which the mirror has to be turned and is also a measure of the speed of the belt representing the ground speed of the aircraft.

It will be apparent that accurate ground speed measurements can be made only when the cradle has been returned to its vertical position, i. e. when the drift angle has been first established. In order to attain the desired accuracy it is required to rotate the mirror about an axis which is parallel to the plane containing the axes of rollers 33 and 34.

To simulate the appearance of ground speed during daylight, it has been found advantageous to employ incandescent lamps with electrical circuit provision to adjust the illuminating intensity. For night conditions, excellent results have been achieved by providing the belt with small luminescent markings used in combination with a stationary source of ultraviolet energy. The luminescent markings when energized give the appearance of street lights, etc.

Figure 2 shows an alternate design in which the servo mechanism using electro-mechanical positioning means is replaced by a mechanical differential 81. The instructors input to the driftmeter is provided by a knob (not shown) on shaft 82, worm 83 fastened thereon, and worm gear 84 fastened to shaft 85. A gear 86 fastened to shaft 85 engages the first input gear 87 of differential 81. The student operates shaft 22, bevel gears 23 and 24, and gear 26 which engages the other input gear 88 of differential 81. Shaft 89 constitutes the output from the differential and is connected to the cradle 31. An indicator 90 indicates the drift angle set into the driftmeter by the instructor. When the student takes a measurement of the drift angle, his reading obtained on dial 28 (Figure 1) should coincide with the indications obtained by means of indicator 90.

Figure 5 shows in a schematic manner a variation of the optical system. A rotatable prism 101 is employed instead of the movable mirror 40 (Figure 1). The prism is capable of pivotal movement about the axis of shaft 102. It will be apparent to those skilled in the art that the prism is held in a supporting structure in such a manner that the path of the light through the prism is not impaired. By tilting the prism, the advance of a selected marking on belt 103 may be seen as a stationary image through eyepiece 104. As described in connection with Figure 1; an image forming lens 105 and a stationary reticle 1416 complete the optical system. Stationary mirrors may be used in order to deflect the light path or to shorten the mechanical configuration. Although the cradle is shown in a horizontal position it will be 'otal motion in response to motion imparted to said ro- 4 apparent that by proper arrangement or reorientation of the prism and/ or the use of stationary mirrors the cradle may occupy any desired angle relative to the horizontal and vertical axis of the supporting structure.

Regarding the general design of electro-mechanical servo mechanisms which employ the combination of a synchro, servo motor and electronic amplifier reference is made to the book entitled Electronic Instruments" by I. A. Greenwood, Jr. et al., Massachusetts Inst. of Technology Radiation Laboratory Series, McGraw-Hill Book Co., Inc., New York, N. Y. 1948, particularly part II subheaded Instrument servo mechanisms.

Several other and further modifications are possible as will be apparent to those skilled in the art. The belt driving means 35 supported on the cradle 31, for in stance, could be mounted on frame 10. Flexible shaft means then could serve as the driving connection between the motor and belt roller 34.

While there have been described and illustrated specific embodiments of the invention, it will be obvious that various changes and modifications may be made therein without departing from the field of the invention which should be limited only by the scope of the appended claims. Other features of the invention disclosed and described are claimed in the co-pending application for Letters Patent Serial No. 419,399 with filing date of March 29, 1954.

What is claimed is:

1. A driftmeter simulator comprising a stationary frame; an electro-mechanical positioning means including a stator and a rotor supported by this frame; the stator of said clectro-mechanical means mounted for rotation about its longitudinal axis relative to said stationary frame; means to displace said stator from an initial position and retain it in said displaced position; a cradle connected to said rotor and being adapted for pivotal motion in response to motion imparted to said rotor; said cradle supporting a movable belt; means to drive said belt; pivotally mounted means for deflecting light in communication with a portion of the belt and receiving an image therefrom, and an optical system for presenting the image received by said deflecting means at a stationary point.

2. A driftmeter simulator comprising a stationary frame; an electromechanical positioning means including a stator and a rotor supported by this frame; the stator of said electro-mechanical means mounted for rotation about its longitudinal axis relative to said stationary frame; means to displace said stator from an initial position and retain it in said displaced position; a cradle coupled to said rotor and being adapted for pivotal motion in response tomotion imparted to said rotor; said cradle sup porting a plurality of rollers; an endless flexible belt having markings supported on said rollers; variable speed drive means adapted to drive said belt; a light deflecting means positioned for communication with a portion of said belt and receiving an image of said markings; an optical system for presenting the image received by said deflecting means at a stationary point, and said deflecting aneans mounted for pivotal motion to produce a stationary image of said markings at said stationary point as the belt traverses a predetermined distance.

3. A driftmeter simulator comprising a stationary frame; an electro-mechanical positioning means including a stator and a rotor supported by this frame; the stator of said electro-mechanical means mounted for rotation about its longitudinal axis relative to said stationary frame; means to angularlyvdisplace said stator from an initial position and retain it in said displaced postion; means to indicate the angular displacement of said stator; a cradle coupled to said rotor and being adapted for pivtor; said cradle supporting at least two spaced rollers having parallel axes of rotation; at flexible, endless belt equipped with markings supported on the rollers; variable speed drive means adapted to drive said belt for rotation system to indicate about said rollers; a light deflecting means positioned for communication with a portion of the belt and receiving an image of said markings; an optical system for presenting said image at a stationary point; said deflecting means mounted for pivotal motion about an axis parallel to the plane containing the axes of said rollers, and means to pivot said deflecting means to produce a stationary image of said markings at said stationary point as the belt traverses a predetermined distance.

4. A driftmeter simulator comprising a stationary frame; an electro-rnechanical positioning means including a stator and a rotor supported by this frame; the stator of said electro-mechanical means mounted for ro tation about its axis relative to said stationary frame; means coupled to said stator for angulanly displacing the stator relative to said frame; means to indicate the angular displacement of said stator; a cradle coupled to said rotor and being adapted for pivotal motion in response to motion imparted to said rotor; said cradle supporting at least two spaced rollers having parallel axes of rotation; a flexible endless belt equipped with discernible markings supported on said rollers and defining a sub stantially straight portion intermediate said rollers; variable speed drive means for driving said belt about said rollers; a movable light deflecting means positioned for communication with the substantially straight portion of the belt and receiving an image of said markings; an optical system for presenting said image at a stationary point; stationary reference markings disposed in said optical pivotal displacement of said cradle; said deflecting means mounted for pivotal motion about an axis parallel to the plane containing the axes of said rollers; and means to pivot said deflecting means to produce a stationary image of selected markings at said stationary point as said markings traverse a predetermined distance along the substantially straight portion of the belt.

5. A driftmeter simulator comprising a stationary frame; an electro-mechanical positioning means including a stator and a rotor supported by this frame; the stator of said electromechanical means mounted for rotation about its axis relative to said stationary frame; means coupled to said stator for angularly displacing the stator relative to said frame; means to indicate the angular displacement of said stator; a cradle coupled to said rotor and being adapted for pivotal motion in response to motion imparted to said rotor; said cradle supporting spaced rollers; a flexible endless belt equipped with discernible markings supported on said rollers and defining a sub stantially straight portion intermediate said rollers; variable speed drive means for driving said belt about said rollers; a movable light deflecting means positioned for scanning the substantially straight portion of the belt and receiving an image of said markings; an optical system including a mirror, a lens and a reticle for presenting said image at a stationary point; said reticle adapted to indicate angular displacement of said cradle; said deflecting means mounted for pivotal motion to receive images from a plurality of markings along the substantially straight portion of the belt; means to pivot said deflecting means to produce a stationary image of a selected mark ing at said stationary point as said marking traverses a predetermined distance along the substantially straight portion of the belt, and means to illuminate that portion of the belt in communication with said deflecting means.

6. A driftmeter simulator comprising a stationary frame; an electro-mechanical positioning means including a stator and a rotor supported by this frame; the stator of said electro-mechanical means mounted for rotation about its axis relative to said stationary frame; means coupled to said stator for angularly displacing the stator relative to said frame; means to indicate the angular displacement of said stator; a cradle coupled to said rotor and being adapted for pivotal motion in response to motion imparted to said rotor; said cradle supporting spaced rollers; a flexible endless belt carrying an aerial photograph With discernible markings supported on said rollers and defining a substantially straight portion intermediate said rollers; belt about said rollers; a movable light deflecting means positioned for scanning the substantially straight portion of the belt and receiving an image of said markings; an optical system including a mirror, a lens and a reticle for presenting said image at a stationary point, said reticle adapted to indicate angular displacement of said cradle; said deflecting means mounted for pivotal motion to receive images from a plurality of markings along the substantially straight portion of the belt; means to pivot said deflecting means to produce a stationary image of a selected marking at said stationary point as said marking traverses a predetermined distance along the substantially straight portion of the belt; means to illuminate that portion of the belt in communuication with said deflecting means, and said means including the'combination of luminescent markings on said belt rendered visible by a source of ultraviolet energy.

References Cited in the file of this patent UNITED STATES PATENTS 2,294,408 Karnes Sept. 1, 1942 2,321,799 Cone et al. June 15, 1943 2,345,744 Glenny Apr. 4, 1944 2,413,633 Jones Dec. 31, 1946 2,428,432 Park Oct. 7, 1947 2,458,448 Tuttle Jan. 4, 1949 2,505,094 Bunyan .Apr. 25, 1950 2,506,998 Dehmel May 9, 1950 2,662,305 Alric Dec. 15, 1953 variable speed drive means for driving said 

